The surgical treatment of hepatic tumors is performed by removal or ablation of the involved tissue based on direct palpation and visual assessment sometimes aided with intraoperative ultrasound (IOUS). A new technology, interactive image-guided surgery (IIGS) displays current surgical positions on tomographic images (CT,MR,PET, etc) and permits the identification of precise working position with respect to previously identified anatomic and/or pathologic landmarks. Thus, the exact location in 3-D space can be shared and correlated throughout an operative procedure and significantly enhance surgical navigation. Engineering concepts and mathematical principles will be used in the development of an innovative IIGS system for hepatic surgery, including image processing for effective segmentation of the liver from abdominal CT scans, image registration to map physical space into image space, and integrated hardware and software development to create a system that can be used in th operating room. The specific aims of the R21 phase of this grant are: 1) Develop an automatic method for 3-D liver segmentation for accurate registration under image-guided hepatic surgery; 2) Develop techniques for track ultrasounds for specific use in image-guided hepatic surgery; 3) Adequately control hepatic motion and develop accurate registration algorithms incorporating liver surface data obtained in real-time with a laser scanner. The focus in the R33 phase of this grant will be on the clinical use of the system, with the eventual goal being image-guided ablation and resection of tumors. The specific aims proposed for years 2-4 of this project are: 1) Strengthen automatic methods for robust liver segmentation and surface registration during image-guided hepatic surgery; 2) Confirm system accuracy in tumor targeting using image-guidance in patients undergoing standard liver resection; 3) Determine th effectiveness of image-guided ablation in patients undergoing liver resection procedures; 4) Use image-guided ablation to accurately target and destroy primary and metastatic hepatic tumors and provide surgical navigation during hepatic resection. We believe that IIGS will significantly enhance currently performed clinical procedures and will permit accurate tumor localization for ablation and resection procedures. This technology also may permit minimally invasive treatment of liver tumors now performed in very limited circumstances. This work will also be carried out as a collaborative project between William Chapman, M.D. in the Department of Hepatobilliary Surgery and Liver Transplantation and Robert Galloway Ph.D., in the Department of Biomedical Engineering and other members within the center for Technology-Guided Therapy at Vanderbilt.